Method of automatically doffing the full bobbin packages from, and donning the empty bobbin tubes onto, the spindles of a preparatory spinning machine equipped with at least one row of spindles and with flyers, each rotatably supported in a flyer head above a spindle, and consisting of two flyer arms and a flyer yoke, as well as an apparatus for implementing the method.
Preparatory spinning machines of this type, also called flyer, are used in the spinning process for staple fibre spinning in the penultimate stage of the manufacturing process. They are used for producing a draftable roving, which is wound onto a big-sized bobbin package and is creeled to the subsequent processing machine, normally the spinning machine. Due to the trend of producing bobbin packages of ever-increasing size, and thus weight, the operation of manually exchanging full bobbin packages against empty bobbin tubes has become ever more difficult for the operating personnel, and thus many attempts have been undertaken already of adapting the shape and construction of the working elements, and particularly that of the spindles and flyers, for establishing the conditions allowing for a mechanisation of the operation.
Thus, a preparatory spinning machine of the type mentioned initially is known from Swiss Pat. No. 442,090, in which each flyer is supported in an upper support, mounted fixedly with respect to the room, and is driven, and supports a donning pinfor the bobbin tube, and in which a vertically movably guided bobbin support member supports the spindle in the form of a short donning pin. As the bobbin support member is lowered for the doffing operation the donning pin of the flyer is lifted off the bobbin tube, in such manner that the bobbin package merely rests on the short donning pin of the spindle. As the bobbin support is lowered further, the distance between the lower end of the donning pin of the flyer and the upper end of the bobbin tube exceeds the depth of penetration of the donning pin of the spindle into the bobbin tube. Owing to this arrangement the full bobbin package now can, after being lifted above the donning pin of the spindle, be moved off at a bias to the spindle and to the longitudinal axis of the machine. An empty bobbin tube also can be brought in at a bias to the spindles and to the longitudinal axis of the machine in the free room or space between the spindle and the flyer, and can be donned onto the donning pin of the spindle by slight lowering. As the bobbin package support member is lifted into the working position the bobbin tube now is brought into the correct position relative to the flyer, with which process the exchange operation is to be considered finished. This device, in which elements for corresponding movements at a bias of the bobbin packages and of the bobbin tubes are provided, realizes the mechanized exchange of the bobbin on a preparatory spinning machine.
This arrangement, however, shows several considerable disadvantages. Thus, the bobbin support member is required to be lowerable over more than the whole bobbin tube length, or outside the normal lift range of the bobbin support member. This implies an unfavourably high position of the working elements during normal machine operation, which involves operational disadvantages.
Furthermore, doffing "at a bias" of the bobbin packages implies blockage of the room or space in front of the machine, namely before the exchange operation by the bobbin tubes held in readiness, and after the operation by the full bobbin packages doffed. The working elements required, formed as fork-shaped grippers which are pivotable about a vertical axis, hamper the operation of the machine at all times.
According to a similar proposal shown in German Pat. No. 2,543,842 there are also provided lowerable spindles and flyers located at fixed level with respect to the room and equipped with a donning pin. In this arrangement, however, the bobbin packages and the bobbin tubes no longer, as in the above mentioned example, are moved at a bias to the spindle and to the longitudinal machine axis, away from the spindle, or to the spindle, respectively, but are moved at a bias to the spindle but parallel to the longitudinal machine axis. For this purpose a transporting belt is provided above the bobbin support member onto which the bobbin tube foot ends of the doffed bobbin packages are placed after the donning pins of the spindles have been lowered still further. The full bobbins thus are moved away from the machine in a vertical position, at a bias to the spindle axis, and in longitudinal direction of the preparatory spinning machine, and thereafter the empty tubes are positioned in the same manner.
This arrangement also shows the above mentioned, operational disadvantages, due to the length of the lowering movement of the bobbin support member which is required. It does not, however, occupy additional room in front of the machine. Due to the presence of the transporting belt, which is to be provided with individual bobbin and tube support members, the arrangement, however, is expensive and, furthermore, requires considerable efforts for maintenance and cleaning.
Furthermore, from U.S. Pat. No. 246,469 there are known preparatory spinning machines equipped with flyers supported in bearings at the upper and at the lower part, i.e. with "closed" flyers, aiming at facilitated doffing operations, with the spindles detachable at the lower part, and by pivoting them about the upper bearing serving as a guide into a position of the bobbin suitable for doffing the bobbin package downward and inclined towards the front.
This arrangement presents the disadvantage that the spindle is to be designed to be detachable, resulting in complicated coupling designs, especially if this principle should be applied at today's usual very high rotational speeds, and that doffing can be effected only from below, which operationally is unfavourable.
Furthermore, according to German Pat. No. 1,012,542, it has also been proposed to use a flyer on preparatory spinning machines, which at its lower end is provided with a running ring, and which is provided with a free flyer head. This flyer furthermore can be pivoted about an axis arranged at right angles to its rotational axis to the running ring, the diameter of which corresponds to the width of the flyer and is mounted thereon. Elastic shape-hugging elements are provided between the flyer and the running ring, which elements snap onto the flyer. For doffing the full bobbin package from the spindle the flyer now is tilted or pivoted laterally, respectively, which is effected by overcoming the fixing forces between the flyer and the running ring, generated by the elastic shape hugging elements.
In addition to great doubt as to the out of round running of this known design of such flyers the top portion of which rotates freely, there prevails a very pronounced danger of damage and injury if accidentally flyers leave their vertical position e.g. under the influence of unbalances, which flyers then can collide mutually. Tilting of the flyer by hand, while the flyer is at a standstill, for doffing the full bobbin packages, also could result in difficulties, as the distance between the flyer head and the drafting arrangement cannot be increased without bringing about the danger of tearing the roving located therebetween.
Furthermore, according to German Patent Publication No. 2,521,057, it has become known, that for facilitating the doffing operation of the bobbin package, the bobbin rail, including the bobbins is pivoted on the bobbin rail support in such manner that the bobbin can be tilted into an inclined position for doffing. Thus, presentation of the bobbin packages for doffing is achieved in a position inclined to the front and upward, to the operating personnel, without, however, making impossible unhampered doffing of the bobbin packages, especially from the innermost row on double row machines. If this principle is to be applied to a preparatory spinning machine with an automatic doffing device, also the operational disadvantages (obstruction of the room in front of the machine) mentioned in connection with the above mentioned Swiss Pat. No. 442,090 would occur. Furthermore, a tiltable design of the heavy bobbin rail, which reciprocates up and down, is problematic as far as the forces involved are concerned.